Both the Liberal Democrats and Conservatives are braced for heavy losses in
this week's local elections – with the Coalition partners on track jointly
to lose up to 1,500 seats.

Labour will be the big winner with Ed Miliband's party set to record its biggest share of the vote in council polls for around a decade.

The Liberal Democrats could lose around 600 seats in Thursday's poll – a third of all those currently held by Nick Clegg's party which are being contested.

A loss on this scale – together with a failure to win the referendum on changing to the Alternative Vote (AV) system, also being held on Thursday – could be enough to prompt behind-the-scene discussions about how long Mr Clegg can continue at the party's helm.

He has already faced criticism from some activists over a U-turn on big increases in university tuition fees and support for Government spending cuts.

Chris Huhne, the Climate Change Secretary, is suspected by fellow ministers of being "on manoeuvres" as a possible alternative leader.

In particular, Lib Dem chiefs are braced for losing control of some of their prized northern councils including Newcastle upon Tyne and Hull.

In Sheffield, where they are currently the largest party, control could pass back to Labour in what would be a significant psychological blow in the city which contains Mr Clegg's parliamentary seat.

However, the Conservatives are also expected to suffer big losses, possibly as many as 800 or 900 seats.

David Cameron's party is defending more than 150 councils and more than 5,000 seats as well as the directly elected mayoralty in Torbay.

Tory sources say losses could total up to 1,100 – but parties traditionally try to massage expectations ahead of polls.

One official said: "We know we are going to get a kicking and I'm sure the Lib Dems will as well.

"Governing parties always suffer heavy losses in midterm elections. We're currently at a high point in terms of seats."

In 2007, the last time equivalent elections were held, the Tories achieved 40 per cent of the national vote, with Labour on 26 per cent in the dying days of Tony Blair's premiership, and the Lib Dems on 24 per cent.

Mr Miliband has attempted to play down suggestions his party will gain 1,000 seats on Thursday, but polling experts strongly believe Labour will achieve this figure – with some pundits putting their likely total gains closer to 1,500.

The last time the party was on more than 40 per cent of the national vote in local elections – a figure it is expected to reach this time – was in 2001.

Mr Miliband has campaigned hard in areas such as East Anglia and the South West – parts of the country where the party failed to make much of an impact even in the early days of Mr Blair's leadership.

The Labour leader has sought to capitalise on Lib Dem unpopularity in areas where Mr Clegg's party has traditionally been the main opponent of the Conservatives, and used a Sunday Telegraphinterview last month to burnish his credentials as the candidate for Middle England.

Overall, he has sought to turn the elections – the first nationwide test of the Coalition's popularity since last year's general election – into a "referendum on government spending cuts".

As well as retaking Sheffield, Labour has its sights on Redcar and Cleveland, Bolton, Ipswich and Blackburn, among others, according to research for this newspaper by John Curtice, professor of politics at Strathclyde University.

For his part, Mr Cameron has warned that Labour councillors will repeat what he sees as the tax-and-spend errors of Gordon Brown's government.

"Labour ran our country into the ground. Don't let them do the same to your council," he said last month, campaigning in Darlington.

"Put another way – don't let Labour do to your council what they did to our country."

Big overall gains for Labour, however, are likely to be tempered by results of Thursday's elections for the Scottish Parliament, where latest polls suggest the Scottish National Party is on course to be well ahead as the largest party with around 60 seats.

Such a result for Alex Salmond's party would cement his position as First Minister and make a referendum on Scottish independence more likely.

The result of elections to the Welsh Assembly are on a knife-edge with some polls suggesting Labour will just obtain a majority.

Up for grabs on Thursday in England are every seat on 127 shire district councils and 30 unitary councils, as well as a third of the seats on 67 shire district councils, 19 unitary councils and all 36 metropolitan district councils – a total of more than 9,400 seats. There are no local elections in London.